The present invention relates to an apparatus and process for the direct reduction of iron oxides and, more particularly, a separator for use in the apparatus and process for separating out metallized iron fines from a stream of hot gases employed in the process.
It is well known in the art of steelmaking to employ processes for the direct reduction of iron containing metals with the object of obtaining metallized iron fines. Such a process and apparatus is disclosed in U.S. Pat. No. 5,082,251. In the process and apparatus disclosed in the '251 patent, a plurality of reduction reactors are connected in series and are used for the sequential reduction of a raw iron ore feed. It is not uncommon in prior art processes and apparatus to employ separators in the reduction reactors for separating out the metallized iron fines from the stream of hot gases used during the reduction process so as to obtain the iron fines which are serially transferred from reactor to reactor. A typical separator used in the processes and apparatus of the prior art is described and shown in U.S. Pat. No. 4,756,729 and U.S. Pat. No. 3,675,401.
Typically, the apparatus for separating out metallized iron fines is constructed from a cylindrical body into which a suspension composed of the solid particles and gas enters tangentially. The gas entrained with the solid particles moves through the cylindrical body in a spiral manner generated by the action of centrifugal force due to the tangential injection of the gas stream. The gas stream with entrained solid particles is then conveyed to a conical extension of the cylindrical body of the separator. The gas stream is accelerated in the conical region wherein the vortex disintegrates and the solid entrained particles are separated out from the gas stream. The particle-free gas stream moves, in a reverse spiral, towards a central orifice in the top of the equipment and the separated solid particles are expelled by a discharge outlet located in the bottom of the separator.
The apparatus for separating out solid particles from stream of hot gases as described above and employed in processes for the direct reduction of iron containing metals suffers from a number of disadvantages. Firstly, the metallized iron fines tend to collect as solid crusts on the inner walls of the equipment, for example, the conical section, which leads to a change in the equipment geometry which ultimately adversely affects throughput of the reduction reactor. Secondly, the metallized iron fines which are separated out as a result of the acceleration in the centrifugal force in the conical region of the equipment may attain a degree of plasticity (due to the high temperature process) which causes them to adhere to the inner walls of the body of the separator thereby reducing equipment capacity to separate out solid particles from the gas stream.
Accordingly, it is the principle object of the present invention to provide an improved apparatus for use in reduction reactors used in processes for the direct reduction of iron containing metals.
It is a particular object of the present invention to provide an improved separator for separating out metallized iron fines from streams of process gases employed in processes and apparatus for the direct reduction of iron oxides.
It is a still further object of the present invention to provide a separator as aforesaid which prohibits the formation of solid crusts on the inner walls of the separator thereby resulting in geometric integrity of same.
It is an again still further object of the present invention to provide a separator as aforesaid which is efficient in separating out metallized iron fines for process gas streams whereby the separated out metallized iron fines are easily expelled from the separator for further processing.
Further objects and advantages of the present invention will be made clear hereinbelow.